An aneurysm is a phenomenon in which the wall of a blood vessel is abnormally dilated due to weakening of the vessel wall. Common areas where aneurysms occur and cause potential medical conditions include the cerebral arteries, coronary arteries, the carotid arteries, the thoracic aorta, and the abdominal aorta. Aneurysms pose a danger because the blood pressure within the aneurysm could cause the vessel to rupture. Vessel rupture, in turn, often causes dramatic negative health consequences, such as a stroke in the case of a cerebral vessel rupture.
In recent decades, the main surgical treatment of ruptured and unruptured intracranial aneurysms has been to expose the aneurysm in an open cranial procedure and to ligate the neck of the aneurysm using surgical clips (“clipping”). These open surgical procedures are associated with significant drawbacks. The surgical procedure is complex and requires experienced surgeons and well equipped surgical facilities. Even with the best surgeons and equipment, patients suffering from such aneurysms are often elderly and weakened from cardiovascular and other diseases. This factor reduces the number of patients eligible for surgery. Even for eligible patients prior to rupture, conventional aneurysm repair has a relatively high mortality rate, usually from 2 to 10%. Morbidity related to the conventional surgery includes myocardial infarction, renal failure, impotence, paralysis, and other conditions. Even with successful surgery, recovery takes several weeks and often requires a lengthy hospital stay. The location of an aneurysm may in many cases be buried in the brain and inaccessible from the outside and thus present no surgical option. In such cases, the aneurysm may only be accessible endovascularly.
Recently, many types of aneurysms have been treated endovascularly. Such techniques typically involve attempting to form a mass within the sac of the aneurysm. Typically, a microcatheter is used to access the aneurysm. The distal tip of the microcatheter is placed within the sac of the aneurysm, and the microcatheter is used to inject embolic material into the sac of the aneurysm. The embolic material includes, for example, detachable coils (e.g., Guglielmi Detachable Coils) or an embolic agent, such as a liquid polymer. The injection of these types of embolic materials suffer from disadvantages, most of which are associated with migration of the embolic material out of the aneurysm into the parent artery. This can cause permanent and irreversible occlusion of the parent artery. Additionally, over-packing the aneurysm is another potential disadvantage which could generate undesirable pressure in the aneurysm. Of particular concern are aneurysms having a wide connection to the blood vessel (e.g., wide neck aneurysms). Wide neck aneurysms have the additional risk that the occluded material will break free of the aneurysm and enter the parent blood vessel. Although treatment of an aneurysm by Detachable Coils is oftentimes long and involves many coils, the result is unpredictable and may not be successful at excluding blood flow from the aneurysm.
There remains, therefore, a need for a device and method for therapeutically treating aneurysms that has the accessibility of endovascular procedures combined with the efficacy of an open procedure without the associated risks.